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Plant of the Week #7: Stachys affinis

Hello everyone, and happy April! Depending on where you are living the spring season may already be thoroughly underway, just beginning or still a faint murmur as you gaze out the window at snow drifts. No matter what climate you may find yourself and however prolonged or brief spring may be it is undeniable how satisfying it is to see the first edible plants (whether wild or cultivated) emerge from the formally frozen soil. They are absolutely delicious and so refreshing after surviving on a winter diet that is all too often very rich but also monotonous and usually lacking in fresh vegetables of all kinds.

If I had to decide on a favorite type of vegetable, it would have to be root crops. There is just something indescribable and incredible about gently teasing a plant out of it’s hidden covering of humus in order to reveal a secret treasure of flavors, textures, calories and nutrition. I may keep with this theme of root crops for the next little while, as the spring is one of the seasons where root crops are often produced by countless plant species and therefore can be procured plentifully for the table.

Today I would like to tell you all about a fascinating perennial herb by the name of Stachys affinis, a plant that is well known in many places but virtually unheard of in others, and I would like nothing more than to help change that. Stachys affinis goes by a variety of different names depending on where in the world it is found wild or intentionally cultivated. Believed to have originated in east Asia, this member of the mint family (Lamiaceae)* is known as Chinese artichoke or artichoke betony, despite not being related to true artichokes at all, although the ornamental betony (Stachys officinalis) is indeed a close relative.

Stachys affinis is also grown in regions across Europe, including France and various places in eastern Europe where this plant and its tubers are known as crosne or chorogi. The plants are tuberous, clump-forming herbaceous perennials which grow to a height of around 2-3 feet by mid-summer. The leaves grow opposite each other on the characteristically square stem (a feature of all if not most members of the mint family), taper to a pointed tip and are usually widest at the base or along the middle of the blade. They also have a rough texture with broadly serrated margins and deeply impressed veins.

Once they are mature and established, the plants produce dazzling spikes of bright pink / purple tubular blossoms which are relished by pollinators of all shapes and sizes. Even if it weren’t for this plant’s edible roots (correctly known as tubers, which serve distinct biological functions compared to roots), the ornamental value of this species is hard to deny. Crosne will grow and produce best in rich, continuously moist soil in full sun conditions except in areas that experience particularly long, hot and humid summers in which case it does enjoy a little bit of afternoon shade.

Therefore the lower-lying areas of your garden where the ground tends to stay moist for longer would be a good choice for this plant, as yields and vigor will be diminished if the soil is allowed to dry out for long periods of time during the summer. Like many tuber-forming plants, Stachys affinis is sensitive to daylight length and so won’t start to produce tubers until after the days begin to shorten considerably, often in late September through to early November, which is about the time in the milder parts of Canada where the ground is starting to become frosted.

Crosne is listed as being hardy to at least USDA zone 4 and higher, however I’m confident that if generously mulched with straw, fallen leaves or mulch and given a protective layer of snow that this species could survive in zone 3. Harvests however would likely be diminished as the weather would get colder and the ground would freeze before the tubers have a chance to grow to a size that would be typical for warmer climates. Alternatively, tubers can also be carefully dug up from he ground in the very early spring as soon as the ground thaws and the soil warms up enough for them to sprout.

One word of warning: once established, this plant is practically impossible to eradicate so make sure that you are introducing it to a part of your garden / property where it can spread without disturbing your layout or interfering with the growth of other plants. Stachys affinis is definitely a candidate for introduction into a naturalized and self-sustaining food ‘forest or ‘field’ or could be cultivated in bins or other containers buried in the ground in order to discourage (prevent is too certain of a word to use in this context) and limit it’s spread.

It’s also important to note that in order to ensure the best harvests possible, it is a good idea to keep this plant trimmed to a maximum height of 6 inches or so, as allowing it to flower will use of valuable stores of energy and nutrients that would otherwise be allocated to forming multitudes of plump tubers for you to collect at the end of the year. Fresh tubers are best planted in the very early spring and allowed to grow throughout the growing season before being harvested in the fall.

Despite how thorough you might think you are being, you will never gather all of the tubers in a given area, which will allow the plant to continue growing and provide another bounty next autumn. If you have ever grown Jerusalem artichokes (Helianthus tuberosa) or ‘sunchokes’ as they are sometimes called,then you know what I mean when you can think that you have gotten all of the tubers out of the ground but are quickly proven wrong in the late spring when you are shocked to see dozens if not hundreds of shoots poking through the soil in the patch you thought you cleared out. The lesson here is to think before you plant!

A closely related species native to Europe and introduced to North America where it now grows wild in certain areas is the marsh hedge-nettle or woundwort (Stachys palustris) which also produces edible tubers that are more elongated with tapered ends and not as segmented as the distinctive shape of crosne. The unique grub-like shape of these tubers adds quite a bit of interest to various dishes to say the least. They have a flavor and texture similar to water chestnuts and are best blanched in hot water for only a couple of minutes so they soften but maintain a delicate crunch.

Since they are so mild and fresh tasting, they are an ideal addition to stir fries or chopped up raw and added to salads or used as a garnish. Prolonged cooking ‘apparently’ ruins them, but it is definitely possibly to add them late to soups, stews or roasted with other vegetables and still made to be delicious prepared in those fashions. It is also easiest to clean them as soon as they are dug from the ground by soaking them in water in order to soften and make dislodging all the soil from in between the nooks and crannies in between the bulbous segments of the tubers easier.

However you look at them, Stachys affinis are a table-worthy curiosity that it hard to pass up if you are a backyard gardener with a lust for exotic food crops, especially if you have a soft spot for root crops like myself. I encourage you to give these fun little ‘grubs’ a chance, as once the plants are established they thrive with disturbance and the patches will slowly grow over the years despite your best efforts to harvest every tuber that you can. A fine candidate for self-perpetuating edible landscapes which are becoming more and more popular as permaculture techniques and ‘lazy’ gardening becomes a more widely accepted and desirable ideology.

* The Lamiaceae is an enormously diverse group of plants which includes oregano, thyme, sage, lemon balm, hyssop and many other favorite culinary and ornamental herbs. Although the Mentha genus is certainly one of the most well known groups in the family, not all groups within the family produce the compounds that give off that characteristic spicy, musky and earthy scent that we associate with plants like spear mint (Mentha spicata) which contains R-(–)-carvone as well as limonene or pepper mint (Mentha x piperita) with contains methone and menthyl acetate.

Thanks for commenting. You are most welcome! That’s what I’m here for. You can order some from Norton’s Naturals. They specialize in interesting and unconventional vegetables that I also recommend investigating.